There is the possibility of file sharing problems with Windows XP when the following circumstances apply:

• The TDBISAMSession PrivateDir property is set to a local folder.

• This local folder has its security permissions set so as to prohibit sharing any of its contents with other users (default under Windows XP).

During a table alteration, optimization, or upgrade, this folder is used to create a new version of the table into which the old contents of the table are copied. When this new version of the table is created in the folder, it will normally inherit the permissions of the folder in which it resides, which in this case is usually restricted from sharing its contents with other users, as noted above. After the process is completed, the original table is deleted and this table is moved into its place. Unfortunately, this version of the table now includes the security permissions of the local folder and not those of the database folder in which it ultimately resides.

The solution to this issue is to make sure that the local folder that you are using for DBISAM sessions includes the same security permissions as the database folder in which the tables normally reside. If you do not want to change the security permissions for the local folder then you should consider creating a special folder for temporary DBISAM tables with the desired permissions.

Note
As of version 4.15 of DBISAM, there is a new TDBISAMEngine property called CreateTempTablesInDatabase. By setting this property to True, you can avoid the above issue altogether by having DBISAM create any temporary tables in the database folder instead of the local folder.